我正在创建一个自定义的NSLayoutConstraint子类，我需要知道布局约束的constant属性当前是否正在为内部状态处理设置动画。换句话说，我需要区分:{//noanimationmyLayoutConstraint.constant=100;}和{//animatedmyLayoutConstraint.constant=100;[UIViewanimateWithDuration:0.2animations:^{[self.myViewThatHasTheConstraintAttachedlayoutIfNeeded];}completion:^(BOOLfinishe